The present invention relates to the general field of intrusion detection systems for secure environments, and more particularly to a system that integrates the outputs of both fixed and mobile intrusion detection sensors in order to provide intelligent assessments of the level of security of the environment.
Most security systems utilize fixed sensors such as motion detectors and/or video cameras positioned at specific locations throughout the environment to be secured. Such environments include buildings, military bases, warehouses, storage yards, factories, and even homes. A very great disadvantage with video camera surveillance is that it requires an alert human to monitor a bank of video displays over long periods of time. If the human becomes distracted or fatigued, he may not notice an intrusion. Another problem with such security systems is that in order to be sensitive enough to detect a potential intrusion, they are subject to nuisance trips. This causes erosion in confidence in these systems. Furthermore, such systems do not provide sufficient resolution to be able to identify the specific nature of an intrusion or its precise location. Further, fixed positioned intrusion detectors are not capable of tracking an intruder's position with any real accuracy.
If the environment to be secured is very large, it becomes economically difficult to provide adequate sensor coverage throughout the entire environment with fixed sensors. Furthermore, the fact that the sensors are positioned at fixed locations makes them vulnerable to being neutralized by a determined intruder.
There exists a tradeoff point wherein it becomes more cost effective to outfit a platform with numerous sensors, and let it travel from zone to zone, as opposed to installing, wiring, and protecting the fixed installation of these same sensors so that all areas within a space are effectively covered. This is obviously a function of the conditions to be monitored and the unit cost of the appropriate sensors, as well as the number of areas and geometric configuration of the space to be protected. Some provision must be made to preclude site vulnerability when the robot is not on station, or perhaps even down for maintenance. For these reasons, a combination of both fixed and mobile sensors is likely to evolve as the appropriate solution in most cases, but obvious problems arise with the operation of a mobile platform in an area protected by permanently installed motion detectors, in that the motion of the robots will set off the fixed alarms.
Therefore, a need exists for a security system which allows one or more mobile robots to operate in an area protected by fixed intrusion detectors. Furthermore, a need exists for an intrusion detection system that is capable of detecting the presence of a potential intrusion, then scrutinizing the potential intrusion with greater resolution to ascertain the nature of the intrusion, then determining the probability of an actual intrusion to minimize nuisance trips, and then providing an intruder alarm if the threat of intrusion exceeds a specific level of confidence that an actual intrusion has occurred.